hasMessage doesn't return the same result as ECDSA.toEthSignedMessageHash

[netanel-utila]

Check existing issues

• I checked there isn't already an issue for the bug I encountered.

Viem Version

2.21.40

Current Behavior

The output of the following code is:

import { encodePacked, keccak256, hashMessage } from 'viem';

const encodedData = encodePacked(
  ['address'],
  ['0x2caB3e8CB41eAbf14A2AD1A7bbb6F48b99A371FB']
);

const hash = keccak256(encodedData);

console.log({
  hash,
  hashMessage: hashMessage(hash)
}); 

{
    "hash": "0x0908ca7eb4f80ef4d25fb57cd0992edb1c82f16799df1d87309cb7845b5f9ed9",
    "hashMessage": "0x6c596e920e23b785a71edac783ba6e8a55defffa756193e6f70808c228d9ddbf"
}

When running the same functionality in Solidity (Remix IDE) the hash is the same but hashMessage is not:

    bytes32 hash = keccak256(
            abi.encodePacked(
                0x2caB3e8CB41eAbf14A2AD1A7bbb6F48b99A371FB
            )
        );

        bytes32 signedMessageHash;
        signedMessageHash = ECDSA.toEthSignedMessageHash(hash);
        
        console.log("hash");
        console.logBytes32(hash);
        console.log("signedMessageHash");
        console.logBytes32(signedMessageHash);


        // hash
        // 0x0908ca7eb4f80ef4d25fb57cd0992edb1c82f16799df1d87309cb7845b5f9ed9
        // signedMessageHash
        // 0x50479e391ec5e0bb0aec6563d9e0112b1cfc737959b2fa5cb2a6ea140d5a64fc

Expected Behavior

Both messageHash should produce the same result

Steps To Reproduce

No response

Link to Minimal Reproducible Example

No response

Anything else?

No response

[jxom]

Need to see implementation of ECDSA.toEthSignedMessageHash

[github-actions]

Hello @netanel-utila.

Please provide a minimal reproduction using StackBlitz, TypeScript Playground (for type issues), or a separate minimal GitHub repository.

Minimal reproductions are required as they save us a lot of time reproducing your config/environment and issue, and allow us to help you faster.

Once a minimal reproduction is added, a team member will confirm it works, then re-open the issue.

[netanel-utila]

It's openzeppelin

https://github.com/OpenZeppelin/openzeppelin-contracts/blob/448efeea6640bbbc09373f03fbc9c88e280147ba/contracts/utils/cryptography/MessageHashUtils.sol#L30

[netanel-utila]

Using etherjs gives the correct result:

const encodedData2 = ethers.utils.solidityPack(
  ['address'],
  ['0x2caB3e8CB41eAbf14A2AD1A7bbb6F48b99A371FB']
);

const hash2 = ethers.utils.keccak256(encodedData2);

// Using ethers.utils.hashMessage to apply the Ethereum-specific prefix for signing
const prefixedHash = ethers.utils.hashMessage(ethers.utils.arrayify(hash2));

console.log({
  hash,
  hashMessage: prefixedHash,
});

[jxom]

You need to pass the raw representation of the message via the raw property on hashMessage:

hashMessage({ raw: hash })

[github-actions]

This issue has been locked since it has been closed for more than 14 days.

If you found a concrete bug or regression related to it, please open a new bug report with a reproduction against the latest Viem version. If you have any questions or comments you can create a new discussion thread.